Keratoconus

Munson's Sign 

  • Non-inflammatory, ectatic corneal disease.

Clinical features:

  • Symptoms:
    • Painless or may become painful in acute corneal hydrops
    • Decreased corneal sensation
    • Decreased vision
    • Distorted vision due to irregular astigmatism, corneal scarring or corneal edema
    • Photophobia
  • Signs:
    • Bilateral, progressive abnormal thinning of either the central or paracentral inferior corneal stroma
    • Onset usually during puberty
    • Munson's sign: a V-shaped dent of the lower lid produced by the conic cornea in downgaze
    • Rizutti's sign: conical reflection on the nasal cornea if light is shined from temporal side
    • Fleischer's ring: a partial or complete iron deposition ring in deep epithelium
    • Vertical Vogt's striae may be evident in deep stroma of the apex of the cone
    • Descemet's membrane rupture may result in acute hydrops with stromal or epithelial edema and subsequent subepithelial central scarring
    • Distortion of the corneal image on keratometry, retinoscopy, keratoscopy, and computerized corneal topography
  • May be associated with a variety of ocular and systemic diseases such as habitual eye rubbing, atopic dermatitis, Down's syndrome, Marfan's syndrome, osteogenesis imperfecta or Ehlers-Danlos syndrome.

Management:

  • Astigmatic spectacle or rigid contact lens correction.
  • Superficial keratectomy or epikeratoplasty may be attempted.
  • Penetrating keratoplasty for advanced cases.
  • Recent development: intrastromal corneal ring implant.